abort('409 input error', "geen bestand aangeleverd");
$filename = ltrim($Args, '/').'.html';
-if (file_exists($filename) and !is_writable($filename))
+if (!preg_match('{^(?:[/a-z0-9-])+\.html$}', $filename))
abort('403 input error', "ongeldige bestandsnaam: $filename");
-if (is_executable($filename))
+if (file_exists($filename) and !is_writable($filename))
abort('403 input error', "onwijzigbaar bestand: $filename");
if (!isset($_POST['body']))